• Electronics and Telecommunications Trends
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• v.17 no.1 s.73
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• pp.32-47
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• 2002

본 고에서는 Beyond IMT-2000 시스템에서 Mobile Access의 무선 전송 기법으로 OFDM 방식의 적용 가능성에 대하여 살펴본다. 현재 사용되는 CDMA 방식은 고속 전송 시 chip rate가 크게 증가하기 때문에, Beyond IMT-2000 시스템의 Mobile Access에서 요구하는 2∼100Mbps의 고속 데이터 전송률을 만족시키기가 용이하지 않다. 반면, OFDM 방식은 주파수 효율이 높고, 주파수 선택적 페이딩 채널에 쉽게 대처할 수 있으며, FFT를 사용하여 고속으로 구현할 수 있기 때문에 고속 데이터 전송 시 적합하다. 본 고에서는 OFDM 방식을 사용한 기존의 통신 시스템의 특징을 살펴본 후, Beyond IMT-2000 시스템 Mobile Access의 전송방식으로 OFDM을 적용할 경우의 기술적인 고려사항과 모의실험 결과에 대하여 서술한다.

• Journal of Science and Technology Studies
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• v.9 no.2
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• pp.1-27
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• 2009

This study aims at reviewing and assessing the characteristics of the Korean Science, Technology and Innovation(STI) policy of the 2000s. Starting from the 2000s, Korea's STI policy began to show a new look as there was a clear voice calling for the new strategy creating a new technological development path and the scope of the policy was expanded to the social and quality of life issues. "Creation" and "integration" are becoming the key words of the STI policy of Korea. However, these new trends are not easy to be diffused or institutionalized because still there is the legacy of the old practice of the "catch-up" period, which focused on economic development as well as the imitation of advanced technologies. As result, the current period of the 2000s shows characteristics of a transitional period where the past and the future coexist.

• Cross-Cultural Studies
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• v.49
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• pp.249-274
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• 2017

The indigenous movement in Ecuador, which has been one of the most successful social movements since the 1980s, has been declining since the 2000s. The rapid disintegration and weakening of the indigenous movement with the emergence of the Correa regime is closely related to the geopolitical realities of Ecuador. This study examines the Pachakutik, an independent political organization, as the reason behind the movement's weakened political power and crisis that was experienced under the Correa regime since the 2000s. Until the early 2000s, the indigenous movement exercised considerable political power through CONAIE. CONAIE formed the Pachakutik, in order to resolve their issues politically through elections. Despite the successes of the 1990s, the electoral strategy since the 2000s led to eventual fragmentation and decline of the indigenous movement. Therefore, the impact of Pachakutik on the growth and decline of the indigenous movement has important implications for the future. The need for expansion through intercultural discourses and strategies rather than electoral strategies cannot be overstated. In other words, new approaches are needed to sustain the indigenous movement.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.1
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• pp.59-65
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• 2008

In security layer in the CDMA2000 1x EV-DO, a standard - C.S0024-a v2.0 is being accomplished under the project of 3GPP2(3rd Generation Partnership Project2). Therefore, a security device is needed to implement the security layer which is defined on the standard document for data transfer security between AT(Access Terminal) and AN(Access Network) on CDMA2000 1x EV-DO environment. This paper realizes the security layer system that can make safe and fast transfer of data between AT and AN. It could be applied to various platform environments by designing and implementing the Security Layer in the CDMA2000 1x EV-DO Security Layer to which applies C.S0024-A v2.0 of 3GPP2.

• Journal of Family Resource Management and Policy Review
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• v.8 no.1
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• pp.29-45
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• 2004

This study compared household's investment behaviors over consumer's ages before and after the economic crisis using 1995 and 2000 National Survey of Family Income and Expenditure in korea. Household's investment behaviors were compared in terms of household's financial statements, amounts and proportions invested in various assets, and rate of return on investments. The proportion invested in securities of all households. In terms of the proportion invested, consumers under 40s increased the proportion invested in insurance while consumers over 50s increased the proportion invested in savings and trusts in 1995 than in 2000. Consumers of all ages increased the proportion invested in securities in 2000 than in 1995. Young households had higher rate of return in 1995 while old households had higher rate of return in 2000.

• Proceedings of the Korea Multimedia Society Conference
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• 2000.11a
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• pp.311-314
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• 2000

IMT-2000과 PCS를 연계 서비스하기 위해, 망 구성과 신호 프로토콜을 기반으로 로밍을 위한 연통 프로토콜을 설계하였다. 먼저 여전히 상당부분의 서비스를 차지하게 될 회선 방식의 음성 서비스에 대하여 기본 호 선정 전차와 해제 절차를 고려하였고, 미래의 주요 서비스로 예상되는 인터넷 서비스를 지원하기 위한 패킷 데이터 서비스의 프로토콜과 그 신호절차 설계를 포함하였다. 설계한 프로토콜은 기존 프로토콜에 대해 변형을 가하지 않기 때문에 시스템에 대한 무리가 없으며, IMT-2000과 PCS의 호 선정시 기본 지상망을 거치지 않기 때문에 효율적이라 할 수 있다

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.2
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• pp.276-283
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• 2003

In this paper, a 2-stage power amplifier(PA) for IMT-2000 handset has been designed and fabricated using SiGe HBT, which has excellent frequency characteristics and linearity, to reduce size and weight instead of existing linearization techniques. DC I-V characteristics and S-parameter of SiGe HBT were simulated by Agilent circuit simulator(ADS), with large signal Gummel-Poon nonlinear circuit model. Then the output and interstage matching circuits were designed to satisfy the high power condition and the high gain condition, respectively. The experimental results showed output power of 27.1dBm and ACLR of 20dB, PAE of 34%, and linear power gain of 18.9dB over frequency ranges from 1920MHz to 1980MHz.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.618-626
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• 2011

Recent development of related technologies and efficient utilization of the entire country for the purpose of railway construction, and plans are being accelerated. the railway noise has been improved by increasing the high speed railway station, and accelerating the existing trains. Nord2000 which is an overseas noise prediction equation could not be applied directly to the domestic railway vehicles. So the specific vehicles in the Nordic countries which is a similar specification to domestic trains should be selected. Nord2000's accuracy was compared to Schall03, CRN's. Prediction of Ground impedance and Roughness class were carried out at different. In this paper, the result of selected vehicles for Nord2000 was as follows. S-1aX2 was for express trains, N-$^*2c$-3b was for Mugunghwa, S-Pass/wood was for Saemaul, N-4a was for freight trains, N-3a was for subway, the calculation time for Nord2000 took longer than others, in addition, Ground absorption was indispensable to calculate a noise map for Nord2000. As a result, CRN's prediction noise levels at Wonju-si was closest to the measurements. However, the predicted noise levels of Nord2000 was the most accurate.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.3
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• pp.150-162
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• 2011

For the period between 1991 and 2009, the annual average of 448 forest fires occurred in Korea. Above all, approximately 94% of the total fires frequently occurred during the spring and fall seasons. Therefore, we need to minimize the damage of forest fire and manage them systematically. In this study, we analyzed the spatio-temporal distribution patterns for the frequency of forest fire occurrences by each city and gun during dry season between 1990s and 2000s using GIS. Then we compared to analyze the frequency of forest fire occurrence by ten-day intervals in 2000s with that in 1990s. As a result of analysis, early April showed the highest frequency of forest fire occurrence in both 1990s and 2000s. Compared to the 1990s and 2000s, the regional change of forest fire showed the most frequent fire events around Chungcheong province. Especially extra 27 fires increased in Daejeon city, and the second most frequent fire had more than 10 fires in Jeolla province and Incheon. However, the number of fire frequency decreased by 12 fires at the end of April in Hongcheon-gun(the province of Gangwon). This is the largest drop over the study period. We consider that this paper will utilize usefully to establish regional counterplan for forest fire prevention by understanding regional forest fire patterns from seasonal change.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.35-38
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• 1999

In this paper, we propose bandwidth management scheme to efficiently guarantee the QoS of various services on ATM based IMT-2000 networks. The proposed bandwidth management scheme consists of the call admission control to reduce a handoff failure probability and the scheduling scheme to efficiently allocate a time slot based on the QoS requirements in wireless links. The simulation results show that the proposed bandwidth scheme has better performance than the previous works in terms of the handoff failure probability and packet delay time.